First off I know zero Japanese, so sorry if this is a stupid question. I seem to remember hearing a while back that all Japanese words, when transliterated to the Latin alphabet, will end in a vowel. From the few Japanese words/names I've seen this seems possible.
Is there any truth to this? If true, does anyone know why that is?
(See the other answers for translate vs. transliterate.)
It's due to Japanese's syllable structure. English allows some spectacularly complicated syllables (strengths being a good maximal example*), but Japanese doesn't - its allowed syllable structure is (C)V(N/Q), where C is any consonant, V is any vowel, N is the nasal ん (which can vary in pronunciation depending on what follows it), and Q is the っ consonant-length-extension-phoneme-thing (which can't occur unless it's before a consonant that can be lengthened).
So you can have words that end in /N/, but most of the time you're going to have a vowel. Primarily this is because almost without exception /N/ only occurs in Chinese loanwords (though a few native Japanese words (especially verb forms) have gained an /N/ since its introduction) - so most native words end in vowels. Indeed, most native words will alternate between consonants and vowels (partly due to Old Japanese not liking adjacent vowels - the most common word shape by -far- is (C)VCV).
There are languages (e.g. most Polynesian ones) which cannot, under any circumstances, have syllables that end in consonants. Japanese used to be that way, but under the influence of Chinese, it has gained two syllable-final consonant phonemes. So you will get words that end in /N/, but mostly words will only end in vowels.
*(English's syllable structure works out to something like (s)(C)(L)V(N/L)(C)(s), where L is either l or r and N is any nasal (n, m, ng) - there are some further rules on which consonants can occur next to each other in certain positions (so trV is okay, but tlV isn't), but that description's mostly accurate. Strengths is pretty much the biggest you can have.)
First off, by 'translate' I assume you mean 'transliterate', to convert text from one script to another. I apologize if this is not what you meant to ask. "猫 = cat" would be a translation; "猫 = neko" would be a transliteration.
To answer the question, Japanese is made up of syllables, all but one of which are vowels (a, i, u, e, o) or a combination of a consonant and a vowel (ka, ki, ku, ke, ko, sa, si, su, se, so, etc.) Check here for a table of the sounds of Japanese.
The one sound which is irregular is the nasal "n" sound.
So, while the vast majority of Japanese words transliterated into the English alphabet will end in a vowel, those which end in "n" will not. Examples of such words include ミカン/mikan (an orange), 画面/gamen (screen) and 来年/rainen (next year).
No, it's not true.
Counterexample
剣 translates to "sword", which does not end in a vowel.
Even when Japanese is transliterated into English, it's not true.
Counterexample
[剣]{けん} is transliterated as "ken" or "kenn", which does not end in a vowel.
What is true, is that many Japanese words, when transliterated into ローマ字 (Latin alphabet) do end in a vowel, because the Japanese writing system is based on syllables (the Japanese "alphabet" thus carries the technical name "syllabary"). A syllable is in all but six cases (the five vowels あいうえお and the "consonant" ん) made up from a consonant followed by a vowel. Any word ending in any other syllable would, in its transliteration into the Latin alphabet, thus end in a vowel. Exception being the "syllable" ん, which is usually transliterated n (or in rare systems nn). That said, historically ん derives from む "mu", which is a proper syllable (ending in a vowel).
